A course commonly taken in college by math, engineering and various other majors. It is a field of mathematics created for the sole reason of torturing anyone who thought calculus was easy. In many cases attending lectures in this class will cause mild to severe brain trauma depending on the competency of the lecturer and the student.

1. An equation with one or more variables relating with their respective derivative(s) at different magnitudes.
2. Differential Equations is a college course used for Math, Physics, Engineering, etc. majors